Dear Gerard,
thanks for alerting us of this Moscow premiere (especially for fans of this great composer like me) !
Btw., your added informations are quite outdated (as is the composer's own home page) - e.g. the
latest symphony available from classical-music-online already carries number 32 and his Symphony No.33
is available from Slonimsky's own (??) YT channel:
One source containing some more recent informations about him is
http://www.remusik.org/en/slonimsky/Downloadable mkv files of the above mentioned concert featuring Slonimsky's 2nd Piano Concerto are also available from
http://intoclassics.net/news/2014-09-18-36708